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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: Timestamp.html 939 2015-05-29 01:16:17Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.kv.raft;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import com.google.common.base.Preconditions;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>/**<a name="line.12"></a>
<span class="sourceLineNo">013</span> * Represents a relative timestamp in milliseconds. Stored as an unsigned integer that cycles after 2&lt;sup&gt;32&lt;/sup&gt;<a name="line.13"></a>
<span class="sourceLineNo">014</span> * milliseconds (about 48 days). Two values to be compared must have been generated within 24 days of each other<a name="line.14"></a>
<span class="sourceLineNo">015</span> * to be ordered correctly.<a name="line.15"></a>
<span class="sourceLineNo">016</span> *<a name="line.16"></a>
<span class="sourceLineNo">017</span> * &lt;p&gt;<a name="line.17"></a>
<span class="sourceLineNo">018</span> * This class uses {@link System#nanoTime}, not {@link System#currentTimeMillis}, and so is immune to changes in the system clock.<a name="line.18"></a>
<span class="sourceLineNo">019</span> *<a name="line.19"></a>
<span class="sourceLineNo">020</span> * &lt;p&gt;<a name="line.20"></a>
<span class="sourceLineNo">021</span> * Instances are immutable.<a name="line.21"></a>
<span class="sourceLineNo">022</span> */<a name="line.22"></a>
<span class="sourceLineNo">023</span>public class Timestamp implements Comparable&lt;Timestamp&gt; {<a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>    // Make timestamps start at zero to facilitate debugging<a name="line.25"></a>
<span class="sourceLineNo">026</span>    private static final int TIME_BASE = Timestamp.milliTime();<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>    private final int millis;<a name="line.28"></a>
<span class="sourceLineNo">029</span><a name="line.29"></a>
<span class="sourceLineNo">030</span>    /**<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * Construtor returning the current time.<a name="line.31"></a>
<span class="sourceLineNo">032</span>     */<a name="line.32"></a>
<span class="sourceLineNo">033</span>    public Timestamp() {<a name="line.33"></a>
<span class="sourceLineNo">034</span>        this(Timestamp.now());<a name="line.34"></a>
<span class="sourceLineNo">035</span>    }<a name="line.35"></a>
<span class="sourceLineNo">036</span><a name="line.36"></a>
<span class="sourceLineNo">037</span>    /**<a name="line.37"></a>
<span class="sourceLineNo">038</span>     * Constructor.<a name="line.38"></a>
<span class="sourceLineNo">039</span>     *<a name="line.39"></a>
<span class="sourceLineNo">040</span>     * @param millis relative milliseconds value from {@link #getMillis}<a name="line.40"></a>
<span class="sourceLineNo">041</span>     */<a name="line.41"></a>
<span class="sourceLineNo">042</span>    public Timestamp(int millis) {<a name="line.42"></a>
<span class="sourceLineNo">043</span>        this.millis = millis;<a name="line.43"></a>
<span class="sourceLineNo">044</span>    }<a name="line.44"></a>
<span class="sourceLineNo">045</span><a name="line.45"></a>
<span class="sourceLineNo">046</span>    /**<a name="line.46"></a>
<span class="sourceLineNo">047</span>     * Get the relative milliseconds value contained by this instance.<a name="line.47"></a>
<span class="sourceLineNo">048</span>     *<a name="line.48"></a>
<span class="sourceLineNo">049</span>     * @return relative millisecond value<a name="line.49"></a>
<span class="sourceLineNo">050</span>     */<a name="line.50"></a>
<span class="sourceLineNo">051</span>    public int getMillis() {<a name="line.51"></a>
<span class="sourceLineNo">052</span>        return this.millis;<a name="line.52"></a>
<span class="sourceLineNo">053</span>    }<a name="line.53"></a>
<span class="sourceLineNo">054</span><a name="line.54"></a>
<span class="sourceLineNo">055</span>    /**<a name="line.55"></a>
<span class="sourceLineNo">056</span>     * Get the number of milliseconds this instance is offset from the current time.<a name="line.56"></a>
<span class="sourceLineNo">057</span>     *<a name="line.57"></a>
<span class="sourceLineNo">058</span>     * @return relative millisecond offset<a name="line.58"></a>
<span class="sourceLineNo">059</span>     */<a name="line.59"></a>
<span class="sourceLineNo">060</span>    public int offsetFromNow() {<a name="line.60"></a>
<span class="sourceLineNo">061</span>        return this.millis - Timestamp.now();<a name="line.61"></a>
<span class="sourceLineNo">062</span>    }<a name="line.62"></a>
<span class="sourceLineNo">063</span><a name="line.63"></a>
<span class="sourceLineNo">064</span>    /**<a name="line.64"></a>
<span class="sourceLineNo">065</span>     * Get the number of milliseconds this instance is offset from the given instance.<a name="line.65"></a>
<span class="sourceLineNo">066</span>     *<a name="line.66"></a>
<span class="sourceLineNo">067</span>     * @param base base timestamp<a name="line.67"></a>
<span class="sourceLineNo">068</span>     * @return relative millisecond offset<a name="line.68"></a>
<span class="sourceLineNo">069</span>     * @throws IllegalArgumentException if {@code base} is null<a name="line.69"></a>
<span class="sourceLineNo">070</span>     */<a name="line.70"></a>
<span class="sourceLineNo">071</span>    public int offsetFrom(Timestamp base) {<a name="line.71"></a>
<span class="sourceLineNo">072</span>        Preconditions.checkArgument(base != null, "null base");<a name="line.72"></a>
<span class="sourceLineNo">073</span>        return this.millis - base.millis;<a name="line.73"></a>
<span class="sourceLineNo">074</span>    }<a name="line.74"></a>
<span class="sourceLineNo">075</span><a name="line.75"></a>
<span class="sourceLineNo">076</span>    /**<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * Return this timestamp offset by the given amount.<a name="line.77"></a>
<span class="sourceLineNo">078</span>     *<a name="line.78"></a>
<span class="sourceLineNo">079</span>     * @param offset offset in milliseconds<a name="line.79"></a>
<span class="sourceLineNo">080</span>     * @return adjusted timestamp<a name="line.80"></a>
<span class="sourceLineNo">081</span>     */<a name="line.81"></a>
<span class="sourceLineNo">082</span>    public Timestamp offset(int offset) {<a name="line.82"></a>
<span class="sourceLineNo">083</span>        return new Timestamp(this.millis + offset);<a name="line.83"></a>
<span class="sourceLineNo">084</span>    }<a name="line.84"></a>
<span class="sourceLineNo">085</span><a name="line.85"></a>
<span class="sourceLineNo">086</span>    /**<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * Determine whether this timestamp is in the past or the future.<a name="line.87"></a>
<span class="sourceLineNo">088</span>     *<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * @return true if this timestamp is in the past<a name="line.89"></a>
<span class="sourceLineNo">090</span>     */<a name="line.90"></a>
<span class="sourceLineNo">091</span>    public boolean hasOccurred() {<a name="line.91"></a>
<span class="sourceLineNo">092</span>        return Timestamp.now() - this.millis &gt;= 0;<a name="line.92"></a>
<span class="sourceLineNo">093</span>    }<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span>    /**<a name="line.95"></a>
<span class="sourceLineNo">096</span>     * Get a {@link Timestamp} in the distant past. The actual returned value is about 12 days ago.<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * @return timestamp value in the distant past<a name="line.98"></a>
<span class="sourceLineNo">099</span>     */<a name="line.99"></a>
<span class="sourceLineNo">100</span>    public static Timestamp distantPast() {<a name="line.100"></a>
<span class="sourceLineNo">101</span>        return new Timestamp(Timestamp.now() - 0x40000000);<a name="line.101"></a>
<span class="sourceLineNo">102</span>    }<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span>// Internal methods<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span>    private static int now() {<a name="line.106"></a>
<span class="sourceLineNo">107</span>        return Timestamp.milliTime() - TIME_BASE;<a name="line.107"></a>
<span class="sourceLineNo">108</span>    }<a name="line.108"></a>
<span class="sourceLineNo">109</span><a name="line.109"></a>
<span class="sourceLineNo">110</span>    private static int milliTime() {<a name="line.110"></a>
<span class="sourceLineNo">111</span>        return (int)(System.nanoTime() / 1000000L);<a name="line.111"></a>
<span class="sourceLineNo">112</span>    }<a name="line.112"></a>
<span class="sourceLineNo">113</span><a name="line.113"></a>
<span class="sourceLineNo">114</span>// Object<a name="line.114"></a>
<span class="sourceLineNo">115</span><a name="line.115"></a>
<span class="sourceLineNo">116</span>    @Override<a name="line.116"></a>
<span class="sourceLineNo">117</span>    public boolean equals(Object obj) {<a name="line.117"></a>
<span class="sourceLineNo">118</span>        if (obj == null || obj.getClass() != this.getClass())<a name="line.118"></a>
<span class="sourceLineNo">119</span>            return false;<a name="line.119"></a>
<span class="sourceLineNo">120</span>        final Timestamp that = (Timestamp)obj;<a name="line.120"></a>
<span class="sourceLineNo">121</span>        return this.millis == that.millis;<a name="line.121"></a>
<span class="sourceLineNo">122</span>    }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>    @Override<a name="line.124"></a>
<span class="sourceLineNo">125</span>    public int hashCode() {<a name="line.125"></a>
<span class="sourceLineNo">126</span>        return this.millis;<a name="line.126"></a>
<span class="sourceLineNo">127</span>    }<a name="line.127"></a>
<span class="sourceLineNo">128</span><a name="line.128"></a>
<span class="sourceLineNo">129</span>    @Override<a name="line.129"></a>
<span class="sourceLineNo">130</span>    public String toString() {<a name="line.130"></a>
<span class="sourceLineNo">131</span>        final long value = this.millis &amp; 0xFFFFFFFFL;<a name="line.131"></a>
<span class="sourceLineNo">132</span>        return String.format("%05d.%03d", value / 1000, value % 1000);<a name="line.132"></a>
<span class="sourceLineNo">133</span>    }<a name="line.133"></a>
<span class="sourceLineNo">134</span><a name="line.134"></a>
<span class="sourceLineNo">135</span>// Comparable<a name="line.135"></a>
<span class="sourceLineNo">136</span><a name="line.136"></a>
<span class="sourceLineNo">137</span>    @Override<a name="line.137"></a>
<span class="sourceLineNo">138</span>    public int compareTo(Timestamp that) {<a name="line.138"></a>
<span class="sourceLineNo">139</span>        Preconditions.checkArgument(this.millis != (that.millis ^ 0x80000000));<a name="line.139"></a>
<span class="sourceLineNo">140</span>        final int diff = this.millis - that.millis;<a name="line.140"></a>
<span class="sourceLineNo">141</span>        return diff &lt; 0 ? -1 : diff &gt; 0 ? 1 : 0;<a name="line.141"></a>
<span class="sourceLineNo">142</span>    }<a name="line.142"></a>
<span class="sourceLineNo">143</span>}<a name="line.143"></a>
<span class="sourceLineNo">144</span><a name="line.144"></a>




























































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